How to Link NinjaTrader with a Broker of your Choice.

I have a strategy that I developed using NinjaTrader. I would like to link it with BlackwoodPro (pacmid.com)

It is not one of their supported brokers. But there has to be a way to create an interface (api).
I know some people who use TradeStation as their platform but have their trades routed to other brokers via some interface.